Metallic structures are treated in numerous ways to prevent or minimize corrosion, such as painting, sealing or anodizing. The corrosion of metallic substances is the deterioration of the substance from reaction with the environment. The most common type of corrosion is oxidation. In selecting the method to protect the metallic structure from corrosion, consideration must be given to the conditions of use, particularly the environment to be encountered and how the method chosen for corrosion protection will affect the functioning of the structure.
The protection of metallic substances by anodizing them is generally economical. The corrosion of metallic substances is related to the metal's conductivity, impurities present, temperature, and oxygen levels. Anodizing slows the rate of corrosion by creating an oxide film on the metallic surface which acts as an anode which resists oxidation. Some metallic substances such as aluminum alloys will to a certain extent naturally form a protective oxide coating. Anodizing while providing corrosion resistance, is undesirable for some applications where the structure must be reflective because anodizing the surface increases absorption of radiation energy. For example, where a metallic surface is to be utilized as a mirror for concentrating solar energy it is desirable that the maximum reflectivity of the surface be maintained to prevent heat absorption by the metallic structure. As a result, the temperature rise in the metallic structure is minimized, and maximum energy is reflected to the desired point.
Thus, there has remained a continuing need to provide a highly reflective surface which exhibits good corrosion resistance.